PACIFIC RAPTOR GOLDEN GATE RAPTOR OBSERVATORY ISSUE 41 FALL MIGRATION PUBLISHED AUGUST 2020 2019 Red-tailed Hawk. Photo: Veronica Pedraza Front Cover Artwork: Sharp-shinned Hawk (Accipiter striatus) migrating past Hawk Hill. 12x16 Gouache painting on paper by Bryce W. Robinson. Bryce is an ornithologist and illustrator who works to integrate visual media and research to better communicate topics in ornithology. You can see more of Bryce's work at www.ornithologi.com. 2 FALL MIGRATION 2019 PACIFIC RAPTOR 41 FEATURE CONTENTS 1 Announcements 3 DIRECTOR'S NOTE Raptors in Light of Climate Change HAWKWATCH 7 The Complex Art of "Seeing" Reptors 9 Measuring the Rate of Raptors BANDING 15 Training the Next Generation of Raptor Biologists 19 Changes in Migrating Accipiters BAND RECOVERIES & ENCOUNTERS 25 GGRO Recovery Data Supports Airport Safety 29 Recent Records 41 Turkey Vulture Update: The Story of 368 43 OUTREACH Five Years of Migratory Story 45 Pinnacles National Park: Unexpected Nest-Mates 47 INTERN INTERVIEW Dr. Linnea Hall 51 PEREGRINATIONS Winter Raptors at Lynch Canyon PACIFIC RAPTOR 3 GGRO bander and docent Lynn Schofield releases a Cooper's Hawk at a weekend Hawk Talk program. Photo: Paula Eberle 4 FALL MIGRATION 2019 INTRODUCTION INTRODUCTION Dear Friend of the GGRO, e write this in September 2020, when many uncertainties about the COVID-19 pandemic remain. For more than three decades, the Parks W Conservancy has invited people to the Golden Gate National Parks to support deep and meaningful ecological work through community science. And when the time is right, when we can assure physical distancing and other safety measures, we look forward to continuing to do exactly that once again. Together, we will cultivate and restore native landscapes, we will monitor at-risk and endangered species, and we will keep a pulse on the bird of prey populations of California at the largest raptor migration site in the Pacific states. Thank you for supporting our important work, as a volunteer, donor or an impassioned bird lover. As you read through this year’s Pacific Raptor, reporting on the 2019 season of the Golden Gate Raptor Observatory, we hope you take great pride in your role in preserving and protecting our wild landscapes. GGRO is one of the Golden Gate National Parks Conservancy’s flagship community science programs, and you are what makes it possible! Thank you for your ongoing support for the Parks Conservancy’s mission and future, and for all that you do to preserve these precious national parklands. • Allen Fish GGRO Director, Golden Gate National Parks Conservancy Christine Lehnertz President & CEO, Golden Gate National Parks Conservancy PACIFIC RAPTOR 5 ANNOUNCEMENTS 2019 PRESENTATIONS AND PUBLICATIONS long with generating an enormous The two UC Davis articles were headed up amount of original information by doctoral candidate and GGRO bander, A on California raptor movements Ryan Bourbour. One was a collaborative and ecology, the GGRO relies on excellent paper with US Fish and Wildlife Service relationships with more than a dozen biologists examining mercury loads in academic labs, government agencies, and feathers at migration stations like GGRO NGO’s to leverage the greatest amount across the United States. The other was of science from our work. Many research a methodological review of a technique projects take years to develop, analyze, and pioneered in the Hull lab using DNA to produce results; more years are required determine the prey species of hawks by to publish. In 2019, our collaborations swabbing the bills and feet of the raptors. resulted in three journal publications, two from Dr. Joshua Hull’s lab at the University of California, Davis, and one from Dr. Chris Briggs’ lab at Hamilton College in New York. Doctoral candidate and GGRO bander Ryan Bourbour. 2018 GGRO Intern Laura Kwasnoski. Photo: Nelia White Photo: Ryan Bourbour 1 FALL MIGRATION 2019 ANNOUNCEMENTS Prey DNA samples collected from talons and beaks of raptors banded at GGRO. Photo: Ryan Bourbour Bourbour, RP, BL Martinico, MM Crane, AC Hull, Kwasnoski, LA, KA Dudus, AM Fish, EV and JM Hull. 2019. Messy eaters: Swabbing Abernathy, and CW Briggs. 2019. Examining prey DNA from the exterior of inconspicuous sublethal effects of anticoagulant rodenticides predators when foraging cannot be observed. on haemosporidian parasitemia and body Ecology and Evolution. doi: 10.1002/ece3.4866 condition in migratory Red-tailed Hawks. Journal of Raptor Research 53 (4): 402-409. Bourbour, RP, BL Martinico, JT Ackerman, MP Herzog, AC Hull, AM Fish, and JM Many other GGRO research projects are Hull. 2019. Interspecies, temporal, and in the works—seeds and saplings moving geographic comparisons of feather mercury toward tree status in the coming years. concentrations in North American raptors Three manuscripts have been submitted for sampled at migration monitoring stations. publication in 2020. If there is a common Ecotoxicology. doi: 10.1007/s10646-019-0216-2 theme in the more than eighty scientific articles produced through the GGRO, it would Hamilton College undergrad and GGRO intern have to be collaboration—between academics Laura Kwasnoski led an analysis looking for and volunteers, between agency biologists health impacts of rat poisons on Red-tailed and grad students—a commitment to getting Hawks banded at GGRO. Laura included the the science done and out to the world. Great work and talents of two other former GGRO gratitude to all of our past and present interns, Kristina Dudus and Emily Abernathy, collaborators for investing your time and in her research. energy with GGRO. • PACIFIC RAPTOR 2 DIRECTOR'S NOTE RAPTOR S I N L I GH T O F CLIMATE CHANGE Allen Fish ast fall, I got word of juvenile birds, so they could a new scientific article track dates for the start and L on climate change and end of the first autumn molt. birds. Three biologists at the Some of these species molt University of Haifa and Tel- before autumn migration, Hai College in Israel—Yosef some after. What did Kian GGRO Director Allen Fish takes a selfie break on a Kiat, Yoni Vortman, and Nir foggy afternoon at Hawk Hill. Photo: Allen Fish and his team find? Sapir—had just published an article titled “Feather moult and bird appearance After plotting their molt data against a measure of are correlated with global warming over the last climate change called Global Mean Temperature 200 years.” What? A 200-year dataset? How is Anomalies (GMTA), they found three results over that possible? And even more amazing: climate the 200+ years of data: (1) the amount of molt change can impact the look of a bird, its very increased for 16 of the 19 songbird species; (2) for plumage? I found a PDF of the original article from ten species that showed different adult plumages Nature Communications and started reading. in males and females, female birds progressed toward adult plumage faster in four species since 1990; and (3) this pattern of increasing CLIMATE CHANGE CORRELATES molt extent over time appeared in all three WITH PLUMAGE CHANGES categories—year-round resident species, short- To obtain a two-century dataset, Kian and team distance, and long-distance migrating species. visited ten major natural history museums across Europe, scoring the extent of molt on 4012 bird To grab a mental picture of why this might be specimens from the years 1805 to 2016. They happening, think of a generic calendar year, January focused on nineteen species of songbirds, only through December, stretched out on a horizontal ALLEN FISH, hired as GGRO Director in 1985, was the Golden Gate National Parks Conservancy’s first bird biologist. With a background in evolutionary ecology from UC Davis, Allen has an interest in bird population responses to urbanness, climate change, and other human impacts. He is equally fascinated by human responses to wild birds. 3 FALL MIGRATION 2019 DIRECTOR'S NOTE axis, left to right. One of the general findings of climate change research in the last decade is that many birds nest earlier as spring temps start earlier (breeding season shifts left). Another finding is that autumn migration is delayed, as winter temps are delayed (migration season shifts right). These two patterns have the net effect of “opening up” the post-breeding juvenile molt “season” that resides between fledging and the onset of migration. Presumably, the bird does not show much overlap in breeding, molt, and migration because each is a very energetically expensive activity. There is a lot more to think about in Kian’s paper and I encourage you to read the original article which, in my mind, deserves a place in history. Why? For one, how many bird studies have 200-year datasets? Also, this is great proof of the value of museum collections, perhaps the most important validation since Dan Anderson crossed the continent to measure 1400 Peregrine Falcon eggshells in This young Red-tailed Hawk resists a light February snow in the mountains of California. Photo: Pamela Rose Hawken the mid-sixties to document the impact of DDT. Hawk in North America. Redshoulders take a great So, what do we know about raptors and climate range of prey, largely what is found in a riparian change from the scientific literature? There forest, from snail to stickleback, shrew to squirrel, are many general patterns and models about and songbird to pheasant. So not only is the how birds in general might respond to climate Redshoulder positioned a bit higher up the trophic change, but do birds of prey present a different ladder than the Honey Buzzard, but as a generalist situation? Maybe a better way to ask this is: do predator it has greater nimbleness in its ability to predatory birds respond differently to climate switch prey types in the face of low prey numbers.